Got an overpayment notice, what now? - what worked for you?

I received a letter saying I was overpaid about $600 on my claim. I would rather hear the honest version than the polite one. The letter mentions an appeal window and a repayment plan. Who should I talk to first?

Read the letter for the appeal deadline and act on it, even if you think you will end up repaying. Then ask about a payment plan.